Cleaning arrangement for rotary regenerative heat exchanger



July 6, 1965 G. D. BRADDON ETAL CLEANING ARRANGEMENT FOR ROTARY REGENERA'I'IVE HEAT EXCHANGER v Filed Aug. 29, 1961 INV EN TORS Y War/mm .0. C/ark A/oyr/ar A /e/h WAZW United States Patent 3,192,997 CLEANING ARRANGEMENT FOR ROTARY V REGENERATIVE HEAT EXCHANGER George D. Braddon, Norman D. Clark, and Aloysius Klein, Wellsville, N.Y., assignors, by mesne assignments, to Combustion Engineering, Inc., a stock corporation of Delaware Filed Aug. 29, 1961, Ser. No. 134,644 6 Claims. (Cl. 165-5) This invention relates to a cleaning arrangement for rotary regenerative heat exchange apparatus, and particularly to means for mechanically removing products of combustion that continuously collect on the surface of such apparatus and subsequently retard the flow of fluid therethrough.

In' rotary heat exchange apparatus of this general type, a rotor carrying a mass of perforate heat absorbent material is rotated about its axis within a concentric housing that is provided with inlet and outlet ducts for a heating fluid and a fluid to be heated in order that heat from the heating fluid may be transferred to the fluid to be heated through the intermediary of the heat absorbent element.

Frequently contained in the gaseous products of combustion that are given off 'during the combustion process in the boiler furnace are certain solid particles or vaporous products that upon cooling solidify and collect on the surface of the heat absorbent material. On occasion these deposits tend to collect most heavily at the cold end of the rotor that lies adjacent the inlet for the fluid to be heated while on other occasions the nature of the deposits is such that they occur most heavily at the opposite or hot end of the rotor.

Cleaning apparatus that includes'washing, lowing and rapping means used either singly or in combination together with still other arrangements have been devised and used to remove the various deposits as they collect on the surface of the heat exchanger in order that the flow passageways will not become restricted and retard or preclude the flow of fluid therethrough.

However certain types of deposits defy removal by the usual cleaning procedures. A prime example of especially troublesome deposits are those that occur in a boiler furnace system that utilizes as its fuel a certain byproduct of the paper manufacturing industry known as black liquor. Here the products of combustion collect heavily at the hot end of the heat exchange apparatus and then tenaciously refuse to be driven off by the usual cleaning methods. This invention is accordingly directed to a particular cleaning arrangement for a rotary regenerative heat exchanger that effectively removes deposits of combustion products from the end edge of rotary heat exchange apparatus, regardless of their type or origin.

A more complete understanding of the invention may be had by referring to the drawing in which:

FIGURE 1 is a sectional elevation of a rotary regenerative heat exchange apparatus showing the general arrangement of the cleaning device.

FIGURE 2 is a top view as seen from line 2--2 of FIGURE 1.

FIGURE 3'is an enlarged fragmentary View showing .the details of the cleaning device.

In the drawings the numeral designates the cylindrical shell of a rotor that is divided into sector shaped compartments by radial partitions 12 that extend to the rotor post 14 to form a series of sectorial compartments 16 therebetween. The rotor compartments 16 contain a mass of perforate heat absorbent material usually taking the form of metallic plates 18 which first absorb heat from hot gases (heating fluid) entering the housing through a duct 28 from a boiler or other source of heat to be discharged after passing over the heat absorbent plates through an outlet duct 32.

As the rotor. is turned slowly about its axis by a motor and reduction gearing arrangement shown schematically at 26, the heated plates 18 are moved into the air stream or other fluid to be heated that is being admitted through 'a duct 22 and then discharged, after passing over the heat absorbent plates,'through an outlet duct 24. The

rotor is surrounded by a housing 34 which is provided at either end adjacent ends of the rotor with end or sector plates 36 which are apertured at 38 and 42 to permit the heating fluid and the fluid to be heated to flow in counterflow relation through spaced portions of the rotor.

In accordance with the invention we provide a rotary brush 44 including a mass of bristles that extend radially outward from an axial shaft 45. The shaft 45 is supported at opposite ends on bearings 48 that are mounted for axial adjustment on fixed housing structure completely independent from the rotor. The brush is of frustoconical configuration having an inner diameter d and an outer diameter d proportional to the inner and outer diameters of the adjacent rotor parts adapted to permit a gear-like intermeshing of the brush and the rotor, when brought into contact with one another. The axially adjustable bearings enable the brush to be moved axially adjacent the rotor. until the bristles of the brush con fronting the rotor extend uniformly into the interstices between element plates and effectively gear the brush to movement of the rotor whereby rotation of the rotor about its axis will cause the brush to rotate about its axis and simultaneously probe the spaces between element plates. As the bristles of the brush probe'the spaces between elements they forcibly remove deposits therefrom and permit the deposits to be reentrained in the fluid stream and exhausted from the rotor. V V

Since the inner andouter diameters d and d of the brush 44 are proportional to the diameter of confronting portions of the rotor, there can be no relative movement therebetween other than an axial penetration or probing of the space between plates of heat absorbent material by the bristles of the brush. Thus all deposits that occur adjacent the end surface of the rotor are sequentially subjected to a positive probing action upon each revolution of the rotor, and a build-up of deposits on the rotor is precluded. By adjusting the bearings axially, it is possible to compensate for bristle wear and thereby provide an optimum cleaning action at all times.

The rotary brush cleaning means of this invention is preferably mounted adjacent the outlet aperture for one of the fluids in order that particulate matter dislodged from the rotor may be quickly entrained in a fluid stream and removed from the rotor. On occasion, however, it may be deemed advantageous to mount the cleaning apparatus at the inlet end of the rotor, and such an arrangement should be considered fully within the scope of the invention.

The construction details of the brush means 44 are not of particular significance to the invention. However, it is important that the materials for construction be selected to provide suitable resistance to heat and abrasion and that the size and stiffness of the radial bristles that comprise the brush be determined in accordance with the size and disposition of the openings for fluid flow through the element and the nature of the deposits that tend to obstruct them.

While this invention has been described with reference to the embodiment illustrated in the drawings, it is evident that'various changes may be made without departing from the spirit of the invention, and it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

We claim:

1.. In a rotary regenerative heat exchange apparatus having a cylindrical housing with end plates at opposite ends thereof that include circumferentially spaced apertures for the flow of a heating fluid and a fluid to be heated, and a rotor mounted concentrically within said housing including a mass of perforate heat absorbent material adapted to be alternately contacted by the heating fluid and the fluid to be heated as the rotor is turned about its axis, cleaning means for the removal of deposits adhering to an end portion of said rotor comprising a brush means rotatably mounted adjacent thereto having bristles adapted to rotate at the same peripheral speed as the adjacent face of the rotor and progressively penetrate the perforate end portion of the heat absorbent material in response to movement of the rotor about its axis.

2. In a rotary regenerative heat exchange apparatus having a cylindrical housing with end plates at opposite ends thereof that include circumferentially spaced apertures for the counterflow of a heating fluid and a fluid to be heated, and a rotor mounted concentrically within said housing including amass of perforate heat absorbent material adapted to be alternately contacted by the heating fluid and the fluid to be heated When the rotor is turned about its axis, cleaning means for the removal of deposits adhering to an end portion of said rotor comprising a brush means rotatably mounted adjacent thereto and extending radially across one of said apertures, said brush means having bristles which move at the same peripheral speed as the adjacent surface of the rotor and sequentially penetrate the perforate end por tion of the rotor in response to rotation of the rotor about its axis.

3. In a rotary regenerative heat exchange apparatus having a cylindrical housing including end plates at opposite ends thereof that include spaced inlet and outlet apertures for the counterflow therethrough of a heating fluid and a fluid to be heated, and a rotor mounted concentrically within said housing including a mass of perforate heat absorbent material adapted to be alternately traversed by the heating fluid and the fluid to be heated when the rotor is rotated about its axis, cleaning means for the removal of deposits that adhere to an end portion of said rotor comprising radially spaced bearing means mounted on housing structure adjacent one of said apertures, a rotatable brush means carried by said bearings having bristles that extend through said aperture and penetrate the perforations in said heat absorbent material to dislodge deposits of particulate material therefrom in response to movement of the rotor about its axis.

4. Rotary regenerative heat exchange apparatus as defined in claim 3 wherein said brush means comprises a frusto-conical section having bristles extending radially outward from its axis of rotation.

5. Rotary regenerative heat exchange apparatus as defined in claim 4 wherein the ratio of the diameter of the rotor to that of contacting brush means is substantially constant throughout the radial extent of the rotor.

6. Rotary regenerative heat exchange apparatus as defined in claim 3 wherein said brush means is mounted adjacent one of said spaced outlet apertures to permit particulate material dislodged from said rotor to be reentrained in fluid being exhausted therefrom.

References Cited by the Examiner UNITED STATES PATENTS 597,187 1/98 Larson 15.21

895,232 8/08 Berkeley 152l 2,372,997 4/45 Yerrick et al 165-5 FOREIGN PATENTS 594,599 6/25 France.

250,172 11/25 Great Britain.

694,282 7/ 53 Great Britain.

CHARLES SUKALO, Primary Examiner.

HERBERT L. MARTIN, ROBERT A. OLEARY,

PERCY L. PATRICK, Examiners. 

1. IN A ROTARY REGENERATIVE HEAT EXCHANGE APPARATUS HAVING A CYLINDRICAL HOUSING WITH END PLATES AT OPPOSITE ENDS THEREOF THAT INCLUDE CIRCUMFERENTIALLY SPACED APERTURES FOR THE FLOW OF A HEATING FLUID AND A FLUID TO BE HEATED, AND A ROTOR MOUNTED CONCENTRICALLY WITHIN SAID HOUSING INCLUDING A MASS OF PERFORATE HEAT ABSORBENT MATERIAL ADPATED TO BE ALTERNATELY CONTACTED BY THE HEATING FLUID AND THE FLUID TO BE HEATED AS THE ROTOR IS TURNED ABOUT ITS AXIS, CLEANING MEANS FOR THE REMOVAL OF DEPOSITS ADHERING TO AN END PORTION OF SAID ROTOR COMPRISING A BRUSH MEANS ROTATABLY MOUNTED ADJACENT THERETO HAVING BRISTLES ADAPTED TO ROTATE AT THE SAME PERIPHERAL SPEED AS THE ADJACENT FACE OF THE ROTOR AND PROGRESSIVELY PENETRATE THE PERFORATE END PORTION OF THE HEAT ABSORBENT MATERIAL IN REPONSE TO MOVEMENT OF THE ROTOR ABOUT ITS AXIS. 